Good looking: Phone screens that do the focusing for you

The lenses in our eyes get stiffer as we age, making it harder to focus on things that are close up. This is why people start to need reading glasses from their 40s onwards. Eventually, nearly everyone will own a pair. But it can be a pain putting on your glasses every time you look at your phone, for instance, assuming you can remember where you put them.

Glasses work by partly focusing light before it hits the eye – so if you are looking at a screen, why not make it do the focusing for you? A team at the Massachusetts Institute of Technology has shown that plastic screen covers can correct for all kinds of vision problems – effectively, the screen wears the glasses. But rather than making plastic covers tailored to individuals’ eyes, the team want to exploit the ability of existing 3D screens to control the direction of light. The idea is that instead of providing a 3D image, users could adjust the screen settings to “pre-focus” light as their eyes require.

Few handheld devices have 3D screens so far, but something similar can be done with software alone. “We know how the eye works so we mathematically invert that and compute the image,” says Daniel Aliaga, a computer vision researcher at Purdue University in West Lafayette, Indiana, who helped develop the idea. The software distorts images on the screen in such a way that it mimics the effect of a lens bending the light rays before they reach the eye. “It looks weird to anyone else but to you …